Packaged semiconductor assemblies and methods for manufacturing such assemblies

ABSTRACT

Packaged semiconductor assemblies including interconnect structures and methods for forming such interconnect structures are disclosed herein. One embodiment of a packaged semiconductor assembly includes a support member having a first bond-site and a die carried by the support member having a second bond-site. An interconnect structure is connected between the first and second bond-sites and includes a wire that is coupled to at least one of the first and second bond-sites. The interconnect structure also includes a third bond-site coupled to the wire between the first and second bond-sites.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 12/973,607filed Dec. 20, 2010, now U.S. Pat. No. 8,232,657, which is a divisionalof U.S. application Ser. No. 11/846,928 filed Aug. 29, 2007, now U.S.Pat. No. 7,855,462, which claims foreign priority benefits of SingaporeApplication No. 200705093-3 filed Jul. 9, 2007, now Singapore Patent No.148901, each of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The present disclosure relates to interconnect structures for packagedsemiconductor assemblies, including stacked semiconductor assemblies,and associated methods for manufacturing such assemblies.

BACKGROUND

Semiconductor processing and packaging techniques are continuallyevolving to meet industry demands for improved performance and reducedsize and cost. Electronic products require packaged semiconductorassemblies with a high density of devices in a relatively small space.For example, the space available for memory devices, processors,displays and other microfeature devices is continually decreasing incell phones, personal digital assistants, laptop computers and manyother products. Accordingly, a need exists to increase the density ofsemiconductor devices and components within the confined footprint ofthe semiconductor assembly. One technique to increase the density ofsemiconductor devices within a given footprint is to stack packagedsemiconductor devices. A challenge with this technique, however, isproviding adequate electrical interconnects within and between thestacked packages.

Conventional interconnects electrically connect the integrated circuitryof a semiconductor device (such as a die) with other devices. Forexample, wire bonds and stud bumps can be used to electrically connectsemiconductor devices to a lead frame and/or a support substrate.Interconnects within a device or package can also be formed by creatinga via in the device and then filling or plugging the via with conductivematerial. FIG. 1 illustrates an existing interconnect 100 including afilled via 110. The via 110 is formed by drilling or etching a holethrough a silicon wafer 112. The interconnect 100 is then formed bydepositing a conductive layer 114 in and around the via 110, andpatterning the conductive layer 114 external to the via 110 to isolatethe conductive layer 114 and provide an appropriate electrical signalroute. The remaining void in the via 110 is filled with a conductivefill material 116. The conductive layer 114 and the conductive fillmaterial 116 electrically connect a pad 117 at a first side of thepackage with a solder ball 118 (or other conductive feature) at a secondside of the package.

One challenge associated with forming the interconnect 100 illustratedin FIG. 1 is that it may be difficult to achieve uniform metallizationin the via. If the metallization within the via is non-uniform, thequality and integrity of the interconnect can decrease. For example,vias having a high aspect ratio (i.e., ratio of the depth to the widthof the opening) are especially difficult to consistently plate and fill.Moreover, in certain circumstances the filling process can trap air inthe via that can cause the interconnect or assembly to crack as the fillmaterial and the assembly harden. Such non-uniformities in themetallization of the via can result in inconsistent electricalconnections and compromise the integrity of the interconnects.

Other challenges associated with existing interconnects are the cost,time and complexity of forming, plating and filling the vias. Formingthe vias by an ablation or drilling process typically requires formingindividual vias in a sequential manner, which increases the processingtime required to form the vias. Simultaneously forming the vias by anetching process can be much faster, but etching can result in viashaving inconsistent sizes. It can also be difficult to achieve a densedistribution of the vias with an etching process. Moreover, the platingand filling steps following the via formation require additionalprocessing time. Accordingly, a need exists to improve interconnects andprocesses for forming interconnects in packaged semiconductor devicesand assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross-sectional view of a portion of an interconnect inaccordance with the prior art.

FIG. 2A is a side cross-sectional view of a semiconductor assembly inaccordance with an embodiment of the invention.

FIGS. 2B-2E are side cross-sectional views illustrating various stagesin a method of forming semiconductor assemblies in accordance with anembodiment of the invention.

FIGS. 3-4B are side cross-sectional views of semiconductor assemblies inaccordance with embodiments of the invention.

FIG. 5 is a flow diagram of a process for forming a semiconductorassembly in accordance with an embodiment of the invention.

FIG. 6A is a side cross-sectional view of a semiconductor assembly inaccordance with an embodiment of the invention.

FIGS. 6B-6C are side cross-sectional views illustrating various stagesin a method of forming semiconductor assemblies in accordance with anembodiment of the invention.

FIG. 6D is a side cross-sectional view of a semiconductor assembly inaccordance with an embodiment of the invention.

FIG. 7 is a flow diagram of a process for forming a semiconductorassembly in accordance with an embodiment of the invention.

FIG. 8A is a side cross-sectional view of a semiconductor assembly inaccordance with an embodiment of the invention.

FIG. 8B is a side cross-sectional view illustrating a stage in a methodof forming semiconductor assemblies in accordance with an embodiment ofthe invention.

FIG. 9 is a flow diagram of a process for forming a semiconductorassembly in accordance with an embodiment of the invention.

FIG. 10 is a schematic illustration of a system that incorporatesinterconnect structures in accordance with embodiments of the invention.

DETAILED DESCRIPTION

Several embodiments are described below with reference to packagedsemiconductor devices and assemblies, and methods of forming packagedsemiconductor devices and assemblies. Many details of the invention aredescribed below with reference to methods of forming devices andassemblies having interconnect structures within and between them. Theterm “semiconductor device” and “semiconductor assembly” are usedthroughout to include a variety of articles of manufacture, includingfor example, semiconductor wafers having active components, individualintegrated circuit dies, packaged dies, and two or more semiconductordevices or assemblies in a stacked configuration. Many specific detailsof certain embodiments are set forth in FIGS. 2A-10 and the followingtext to provide a thorough understanding of these embodiments. Severalother embodiments of the invention can have different configurations,components and/or processes than those described in this section. Aperson skilled in the art, therefore, will appreciate that the inventionmay have additional embodiments and may be practiced without severaldetails of the embodiments shown in FIGS. 2A-10.

FIG. 2A is a cross-sectional view of a semiconductor assembly 200 inaccordance with a particular embodiment. The assembly 200 includes asupport member 210 having one or more first bond-sites 211 (e.g., firstbond-sites 211 a and 211 b shown in FIG. 2A). The support member 210carries a die 220 that can include any of a variety of semiconductordevices having a desired configuration. For example, the die 220 caninclude a dynamic or static random access memory, a flash memory, amicroprocessor, or an application-specific integrated circuit. The die220 has one or more second bond-sites 222, only one of which is visiblein FIG. 2A. An adhesive layer 224 or other structure attaches the die220 to the support member 210. One or more interconnect structures 230(e.g., first, second and third interconnect structures 230 a, 230 b and230 c shown in FIG. 2A) electrically connect corresponding firstbond-sites 211 to corresponding second bond-sites 222. The interconnectstructures 230 can include a wire 232, a redistribution structure 240and one or more third bond-sites 260 at a surface of the assembly 200.

For the purposes of this disclosure, a wire refers generally to apre-formed conductive element that is attached to and/or betweenbond-sites, as opposed to redistribution layer lines and vias that areformed in-situ, e.g., using deposition techniques. The wire, forexample, can include a wire bond or a stud bump. Wire bonds and studbumps can be formed using wire bonding techniques including, but notlimited to, forming a ball-like structure at the end of the wire andattaching the end of the wire to a bond-site, e.g., by applying heat,mechanical force and/or ultrasonic energy. When forming wire bonds, thewire can be looped and attached to another bond-site, and when formingstud bumps, the wire can be cut or broken after attachment to a singlebond-site. One skilled in the art will appreciate that differenttechniques can be used for forming the wire bonds. For example, incertain embodiments stand-off stitch bonding techniques (as used byKulicke and Soffa Industries, Inc., Willow Grove, Pa.) can be useful forbond-sites having a limited size. In addition, the order in which thebond-sites are connected can differ. For example, the wire bond can beattached to the first bond-sites 211 first, and then to the secondbond-sites 222, or vice versa.

The assembly 200 illustrated in FIG. 2A further includes an encapsulant228 disposed at least partially over and/or around the support member210, the die 220 and the interconnect structures 230 to protect thesecomponents. As explained in more detail below, the interconnectstructures 230 can provide high quality interconnections between thecomponents of the assembly 200 and can be formed with simpler processingsteps than those associated with existing interconnects.

In the embodiment illustrated in FIG. 2A, a representative firstinterconnect structure 230 a includes a wire 232 that is attachedbetween the first bond-site 211 a and the second bond-site 222. In thisembodiment, the wire 232 is a single, continuous wire bond 234 that hasbeen looped between the first bond-site 211 a and the correspondingsecond bond-site 222. As such, the wire 232 provides a uniformelectrical connection between the support member 210 and the die 220without requiring the complex process of forming, plating and fillingthe vias typically used for conventional interconnects. Instead offorming and filling vias, the wire 232 connects the bond-sites (or otherdesired components) before the attached die 220 is encapsulated. Thewire 232 is generally composed of a conductive material, such as nickel,copper, gold, silver, platinum, alloys of these metals, and/or any otherconductive material suitable for wire bonding techniques. Thecharacteristics of the wire 232 can be selected based on device-specificprocessing or performance needs. For example, the wire 232 can have adiameter, geometry (e.g., round cross-section or flat cross-section),and/or modulus of elasticity selected to satisfy performance andintegration requirements.

The first interconnect structure 230 a illustrated in FIG. 2A alsoincludes an intermediate segment 236 of the wire bond 234, which isconnected to the redistribution structure 240. The intermediate segment236 is spaced apart from and generally parallel to the die 220. As such,the intermediate segment 236 provides an elongated section aligned alongthe major axis of the wire 232 for connecting with the redistributionstructure 240. This arrangement can enhance the integrity of theconnection with the redistribution structure 240. The redistributionstructure 240 can be used to position corresponding third bond-sites 260relative to the first bond-site 211 a and the second bond-site 222. Aconductive member 262, such as a solder ball, can be coupled to thethird bond-site 260 to provide electrical connections to devicesexternal to the assembly 200. In certain embodiments, the firstinterconnect structure 230 a does not include a redistribution structure240, but rather the third bond-sites 260 can be attached directly to aportion of the wire bond 234 between the first bond-site 211 a and thesecond bond-site 222.

The assembly 200 can include other interconnect structures 230 (e.g.,the second interconnect structure 230 b and a multiple thirdinterconnect structures 230 c shown in FIG. 2A) having featuresgenerally similar to those of the representative first interconnectstructure 230 a described above. For example, the second interconnectstructure 230 b shown toward the right side of FIG. 2A can include awire 232 connected between a corresponding first bond-site 211 b and acorresponding second bond-site of the die 220 that is out of the planeof FIG. 2A and not visible. The third interconnect structures 230 cshown adjacent to the second interconnect structure 230 b also includewires 232 (cross-sectional portions of which are visible in FIG. 2A)that extend transverse to the plane of FIG. 2A, and are attached betweencorresponding first bond-sites and second bond-sites that are notvisible in FIG. 2A. These interconnect structures 230 b and 230 c canalso include corresponding redistribution structures 240 that arecoupled between intermediate segments of the wires 232 and correspondingthird bond-sites 260.

In the embodiment illustrated in FIG. 2A, the support member 210includes a prepackaged die 212. The die 212 can be a known good die thathas been tested prior to being packaged in a die encapsulant 214. Thedie 212 can include multiple die bond-sites 216, a representative one ofwhich is shown in FIG. 2A connected to the first bond-site 211 a with adie redistribution structure 218. Other redistribution structures (notvisible in FIG. 2A) can connect the die 212 to other first bond-sites,e.g., the first bond-site 211 b toward the right side of FIG. 2A. Thedie redistribution structure 218 typically includes conductive lines andvias 217, along with one or more dielectric layers 219, and connects thedie bond-site 216 with the first bond-site 211 using known depositionand patterning techniques. In other embodiments described below, thesupport member 210 can include other semiconductor devices orcomponents, such as a bare die or a layered substrate (e.g., a printedcircuit board).

The assembly 200 and the interconnect structures 230 have beencompletely formed in the embodiment illustrated in FIG. 2A. FIGS. 2B-2Edescribed below illustrate techniques for forming the assembly 200 shownin FIG. 2A. FIGS. 3-10 illustrate other semiconductor assemblies,methods for forming semiconductor assemblies, and a representativesystem in accordance with several embodiments. Like reference charactersrefer generally to like components in FIGS. 2A-10 and thus thedescription of many of these components will not be repeated withrespect to FIGS. 2B-10.

FIG. 2B illustrates a stage at which the die 220 has been attached tothe support member 210 with the adhesive layer 224. The adhesive layer224 can be applied to the support member 210 and/or the die 220, and caninclude any of a variety of suitable tapes, polymers or otherstructures, as is known in the art.

In FIG. 2C, the wires 232 of the interconnect structures 230 areconnected to the first bond-sites 211 a, 211 b (as well as other firstbond-sites not visible in FIG. 2C), and to the second bond-sites 222(one of which is shown in FIG. 2C). For example, the wire 232 of thefirst interconnect structure 230 a can be a continuous wire bond 234that is attached between the first bond-site 211 a and the secondbond-site 222 using existing wire bonding techniques, such as, forexample, stand-off stitch bonding. Accordingly, the wire bond 234 canprovide a robust connection between the support member 210 and theattached die 220, and can be attached to the first bond-site 211 a andthe second bond-site 222 relatively quickly. In this configuration, theintermediate segment 236 of the wire bond 234 is spaced apart from andgenerally parallel to the attached die 220 to facilitate subsequentelectrical connections. As discussed further below, in certainembodiments the intermediate segment 236 can be at least partiallyexposed from the encapsulant 228 and connected to the redistributionstructure 240.

FIG. 2D illustrates a stage at which the encapsulant 228 is disposedover the interconnect structures 230 and the attached die 220, forexample in a molding process. The encapsulant 228 protects the attacheddie 220 from contamination (e.g., due to moisture, particles, etc.) andalso electrically isolates the wires 232 and other conductive componentsof the interconnect structures 230 and the assembly 200. A thickness Tof the encapsulant 228 can be controlled to have different values indifferent embodiments. For example, in certain embodiments, thethickness T can have a first value T₁ so as to completely cover thewires 232, including the intermediate segments 236. In otherembodiments, the thickness T can have a second value T₂ so that theintermediate segments 236 of the wires 232 are at least partiallyexposed to the region outside of the encapsulant 228. If the thickness Thas a value greater than T₂ (e.g., T₁), then material removal steps canbe used to expose the intermediate segments 236. For example, theencapsulant 228 can be planarized and/or etched to at least partiallyexpose the intermediate segments 236. If the intermediate segments 236remain exposed at the end of the encapsulation process, then thematerial removal steps may not be required. In certain embodiments, thematerial removal steps can remove the encapsulant 228 to a thicknesshaving a third value T₃, such that the intermediate segments 236 havebeen removed and each wire 232 is no longer continuous between the firstbond-sites 211 and the second bond-sites 222. In any of theseembodiments, a subsequently-disposed redistribution structure iselectrically connected to the exposed portions of the wires 232. FIG. 2Dalso illustrates another configuration of the wire bond 234 (shown inbroken lines) that can include an intermediate segment 236 a having afirst portion 237 that projects from or is accessible through theencapsulant 228, and a second portion 239 that generally slopes towardsthe second bond-site 222. In this embodiment, the first portion 237provides an access location for a bond-site that can be attacheddirectly to the intermediate portion 236 a of the wire bond 234 withouta redistribution structure.

FIG. 2E illustrates a stage at which the redistribution structure 240 isformed at an exposed face of the encapsulant 228, and is electricallyconnected to and forms part of the interconnect structures 230 at theexposed intermediate segments 236. For example, the redistributionstructure 240 can include a conductive layer 242 deposited directly onthe exposed intermediate segments 236 of the wires 232 (some of whichare elongated transverse to the plane of FIG. 2E). The intermediatesegments 236 can provide an elongated contact area for the conductivelayer 242.

In embodiments where the thickness T of the encapsulant 228 has a valueless than T₂ (e.g., T₃), the intermediate segments 236 are removed alongwith the adjacent encapsulant 228. Accordingly, the redistributionstructure 240 is connected to exposed cross-sectional surfaces of thewires 232 that are generally transverse to the longitudinal axes of thewires 232 and spaced apart from the first and second bond-sites 211 and222. In these embodiments and embodiments described below with referenceto FIGS. 3-4B, the interconnect structures 230 have materialdiscontinuities along the electrical path between the first and secondbond-sites 211 and 222.

In any of the foregoing embodiments, the redistribution structure 240can also include a dielectric layer 244 that is disposed on theconductive layer 242 and patterned to expose the portions of theconductive layer 242 that form and/or connect to the third bond-sites260. The third bond-sites 260 provide electrical connections from theredistribution structure 240 to the conductive members 262, which are inturn accessible from outside the assembly 200. In an embodiment in whichthe wire bond 234 includes the sloped intermediate segment 236 a(illustrated in broken lines in FIG. 2D), the third bond-sites 260 canbe formed at and attached directly to the first portion 237 of the wirebonds 234 without the redistribution structure 240. Accordingly, theinterconnect structures 230 can provide robust electrical connectionsbetween the first and second bond-sites 211 and 222, as well as to theconductive members 262 and external devices that are connectable to theconductive members 262.

FIG. 3 is a cross-sectional view of an assembly 300 configured inaccordance with another embodiment. The assembly 300 is generallysimilar to the assembly 200 described above with respect to FIGS. 2A-2E;however in this embodiment the assembly 300 includes interconnectstructures 330 having wires 332 in the form of discrete stud bumps 334rather than the continuous uninterrupted wire bonds 234 described above.Accordingly, in this embodiment the interconnect structures 330 havematerial discontinuities spaced apart from and between the firstbond-sites 211 and the second bond-sites 222.

FIG. 3 illustrates a processing stage at which individual stud bumps 334have been coupled to the first bond-sites 211 (shown as first bond-sites211 a and 211 b) and the second bond-site 222, and have been at leastpartially encased with the encapsulant material 228. Individual studbumps 334 are formed using the wire bonding techniques described aboveand include a base portion 335 coupled to the corresponding bond-site211 or 222, and a short wire segment 337 extending from the base portion335. The stud bumps 334 can be attached directly to the correspondingfirst bond-site 211 or the corresponding second bond-site 222, or to anintermediate structure, such as a conductive pedestal 333. For example,a representative interconnect structure 330 a shown toward the left sideof FIG. 3 includes stud bumps 334 that are attached directly to thefirst bond-site 211 a and the second bond-site 222. Anotherrepresentative interconnect structure 330 b shown toward the right sideof FIG. 3 includes a stud bump 334 that is coupled to the firstbond-site 211 b via the conductive pedestal 333. The pedestal 333 can beformed using known patterning and deposition techniques, and can projectfrom the first bond-site 211 b to a predetermined height. The pedestal333 can space the attached wire 332 away from the first bond-site 211 band decrease the length of the wire 332. Decreasing the wire length canreduce or eliminate “wire sweep” or movement of the wire 332 during theencapsulation process. Though not shown in FIG. 3, a similar techniquecan be used to space the wires 232 described above with reference toFIGS. 2A-2E away from the corresponding bond-sites, and reduce oreliminate wire sweep in a generally similar manner.

As illustrated in FIG. 3, the encapsulant 228 is molded around the studbumps 334 and the pedestal 333 to protect and electrically isolate thesecomponents. The thickness T of the encapsulant 228 can be controlled atthe molding stage and/or with material removal steps. For example, theencapsulant 228 can be disposed to completely cover the stud bumps 334(as illustrated by the first thickness T₁), and then a portion of theencapsulant 228 and the stud bumps 335 can be removed (as illustrated bythe second thickness T₂) to expose the ends of the stud bumps 334. Inanother embodiment, the stud bumps 334 can extend only to the thicknessT₂ prior to encapsulation, and the mold cavity can be short enough toprevent the ends of the stud bumps 334 from being encapsulated. Ineither embodiment, the assembly 300 can then be further processed, forexample, by forming a redistribution structure electrically connected tothe exposed portions of the stud bumps 334. The redistribution structurecan include third bond-sites or other electrical connection sitesaccessible from the exterior of the assembly 300, using techniquesgenerally similar to those described above with reference to FIGS.2A-2E.

In certain embodiments, the support member 210 of the assemblies 200 and300 described above can include semiconductor devices other than theprepackaged die 212. FIGS. 4A and 4B, for example, are cross-sectionalillustrations of assemblies 400 a and 400 b respectively, that aregenerally similar to the assemblies described above (including wires 232that can be wire bonds or stud bumps), except that the support membersof the assemblies 400 a and 400 b include other devices. Referring firstto FIG. 4A, the assembly 400 a includes a support member 410 a that is abare (e.g., unpackaged) die 412. As such, the die 412 includes anexposed inactive side 413 a opposite an active side 413 b. Accordingly,when the assembly is encapsulated, the encapsulant 228 can be disposedover at least a portion of the bare die 412, as well as the interconnectstructures 230 and the attached die 220. The inactive side 413 a canremain exposed after encapsulation (as shown in FIG. 4A), or it can becovered with the encapsulant 228.

Referring to FIG. 4B, the assembly 400 b includes a support member 410 bthat in turn includes a substrate member 417 (e.g., a printed circuitboard), having one or more conductive layers but no active semiconductordevices. The substrate 417 can include a substrate redistributionstructure 418 that connects components within and to the substrate 417.For example, the substrate redistribution structure 418 can connect thefirst bond-sites 211 to substrate bond-sites 460 at a side of thesubstrate 417 opposite the attached die 220. A plurality of conductivemembers 462, (e.g., solder balls), can be coupled to the substratebond-sites 460. Accordingly, the assembly 400 b can be arranged in astack with other assemblies, with the conductive members 262, 462accessible for electrical connections at both sides of the assembly 400b.

Several embodiments of the interconnect structures described above canprovide quality interconnections, consistent electrical properties, andreduced manufacturing time. For example, the interconnect structuresthat include the wire bonds 234 illustrated in FIGS. 2A-2E can provide acontinuous connection between the first bond-sites 211 and the secondbond-sites 222. Both the wire bonds 234 and the stud bumps 334 (both ofwhich can include wires 232) illustrated in FIGS. 2A-4B are formedbefore the corresponding assembly is encapsulated, and can thus formvoid-free interconnects without the need for forming and plating highaspect ratio vias. Such interconnects can be more robust than the platedand filled vias associated with existing interconnects. Additionally,attaching the wire bonds 234 and the stud bumps 334 to the correspondingbond-sites and disposing the encapsulant 228 over the wire bonds 234 andstud bumps 334 can be a relatively fast and cost effective method offorming the interconnect structures. For example, this process caneliminate the patterning, etching, plating and filling steps associatedwith forming existing interconnects.

FIG. 5 is a flow diagram illustrating an embodiment of a process 500 forforming a semiconductor assembly. In this embodiment, the process 500includes attaching a support member having a first bond-site to a diehaving a second bond-site (block 505). The support member can include aprepackaged die, a bare die, a layered substrate, or other device havingconductive and/or semiconductor features. The process further includesattaching a wire to at least one of the first and second bond-sites(block 510). The wire can be a continuous wire bond with opposing endsconnected to each of the first and second bond-sites, or the wire caninclude discrete stud bumps or portions of a wire bond individuallydisposed at each of the first and second bond-sites. The process furtherincludes encasing at least a portion of the wire and the first andsecond bond-sites with an encapsulant (block 515). A thickness of theencapsulant can be controlled such that the encapsulant completelycovers the wire, or such that a portion or segment of the wire is atleast partially exposed from the encapsulant. In certain embodiments,the encapsulant can be partially removed to expose an intermediatesegment of the wire at a face of the encapsulant. The intermediatesegment of the wire can be aligned along a longitudinal axis of the wireand can be generally parallel to the face of the encapsulant between thefirst and second bond-sites. In other embodiments, removing theencapsulant exposes ends of the wire that are generally transverse tothe longitudinal axis of the wire.

The process 500 further includes coupling a third bond-site to the wire(block 520). In certain embodiments, the process can further includeforming a redistribution structure at a face of the encapsulant spacedapart from the die. The redistribution structure can be connected to theintermediate segment of the wire between the first and second bond-sitesor to the exposed ends of the wire, and the third bond-site can beconnected to the redistribution structure. In other embodiments, thethird bond-site can be connected directly to the wire or coupled to thewire with structures other than a redistribution structure.

FIG. 6A is a cross-sectional view of an assembly 600 a configured inaccordance with another embodiment. Certain aspects of the assembly 600a shown in FIG. 6A are generally similar to the assemblies describedabove; however in this embodiment, the assembly 600 a has interconnectstructures 630 that do not include a wire 232 (e.g., a wire bond 234 orstud bump 334, described above) between the first bond-sites 211 a, 211b and the second bond-sites 222. Instead, the interconnect structures630 include conductive pedestals 333 attached to the first bond-sites211, and a redistribution structure 640, including third bond-sites 660,that directly connects the pedestals 333 to the second bond-sites 222.For example, a representative first interconnect structure 630 aincludes a redistribution structure 640 directly coupled to the pedestal333 through a shallow via 627 in the encapsulant 228. Accordingly, theredistribution structure 640 includes a portion 646 that extends intothe via 627 and contacts the pedestal 333. The presence of the pedestal333 reduces the depth and aspect ratio of the via 627 and can thereforeimprove the manufacturability and reliability of the interconnectstructures 630.

A representative second interconnect structure 630 b is generallysimilar to the first interconnect structure 630 a; however, the secondinterconnect structure 630 b includes a conductive member 262 (e.g., asolder ball) positioned directly over the corresponding first bond-site211 b. A conductive material 648 (e.g., a thin conductive layer) can bedisposed on a portion 646 of the redistribution structure 640 in theshallow via 627 to facilitate the connection with the conductive member262. A base portion 664 of the conductive member 262 is reflowed andcoupled to the conductive material 648, thereby connecting and theconductive member 262 to the first bond-site 211 b via the pedestal 333.In this embodiment, the conductive sidewalls of the via 627 can provideadditional electrical contact area and structural support for theconductive member 262.

FIGS. 6B and 6C illustrate representative stages in a method of formingthe assembly 600 a and the interconnect structures 630 of FIG. 6A inaccordance with one embodiment. FIG. 6B, more specifically, illustratesa stage at which the shallow vias 627 have been formed through theencapsulant 228 to expose the pedestals 333. The pedestals 333 areinitially formed at the first bond-sites 211, as described above withreference to FIG. 3. The encapsulant 228 is then disposed over thepedestals 333 and around the attached die 220, and has an outer surfacethat is generally coplanar with an active side 213 of the attached die220. The active side 213 of the attached die 220 carries the secondbond-site 222 and is protected from being covered by the encapsulant228. The shallow vias 627 are then formed through the encapsulant 228and terminate at a surface 628 of the pedestals 333 spaced apart fromthe support member 210. In certain embodiments, the vias 627 can beformed by laser drilling or etching through the encapsulant 228 to thepedestals 333, and the vias 627 can have a depth that is less than aheight of the pedestals 333. The presence of the pedestals 333 reducesthe required depth of the vias 627 and can accordingly reduce oreliminate some of the challenges associated with forming, plating andfilling vias having a high aspect ratio. Moreover, the pedestals 333 canreduce the likelihood of damage to the support member 210 or componentsbeneath the pedestals 333 because the vias 627 terminate at the upwardlyfacing surface 628 of the pedestals 333.

FIG. 6C illustrates a stage at which the redistribution structure 640has been formed proximate to the active side 213 of the die 220. Thefirst interconnect structure 630 a has a corresponding redistributionstructure 640 that includes a conductive layer 642 extending into theshallow via 627 and coupled to the pedestal 333. The pedestal 333provides a wide connection area for the portion 646 of the conductivelayer 642 in the via 627 and a good thermal pathway away from the firstbond-site 211 a. A dielectric layer 644 is disposed on the conductivelayer 642 to fill the remainder of the shallow via 627, protect theinterconnect structure 630 a, and/or electrically isolate the thirdbond-sites 660. The second interconnect structure 630 b is generallysimilar to the first interconnect structure 630 a, except that theconductive portion 646 in the shallow via 627 is not covered and filledwith the dielectric layer 644. Rather, the conductive material 648 isdisposed in the shallow via 627 to contact at least a portion of aconductive member 262 (e.g., a solder ball) illustrated in FIG. 6A.

FIG. 6D is a cross-sectional view of an assembly 600 b configured inaccordance with another embodiment of the invention. In this embodiment,the assembly 600 b includes a first side 601 and an oppositely-facingsecond side 602, with interconnect structures 630 providing electricalaccess to the assembly 600 b from both the first side 601 and the secondside 602. For example, portions of the redistribution structure 640toward the second side 602 include fourth bond-sites 661 that areaccessible from the second side 602 of the assembly 600 b and can beconnected to corresponding conductive members 262 (e.g., solder balls).Accordingly, the assembly 600 b can have a “double sided” configuration,suitable for stacking and/or inverted attachment arrangements. In thisembodiment, the pedestals 333 and/or the first bond-sites 211 a, 211 bare accessed with vias 629 that extend through the packaging material214 of the support member 210 from the second side 602 of the assembly600 b. The vias 629 can be formed and processed in a manner similar tothat for the vias 627 described above to provide access and electricalconnection to the pedestals 333.

FIG. 7 is flow diagram illustrating a process 700 for forming asemiconductor assembly in accordance with an embodiment generallysimilar to those described above with reference to FIGS. 6A-6D. In thisembodiment, the process 700 includes forming a conductive pedestal at afirst bond-site carried by a support member (block 705). The pedestalhas a surface spaced apart from the support member, which can include aprepackaged die, a bare die, a layered substrate or other device thatincludes conductive and/or semiconductive features. The process furtherincludes attaching the support member to a die having a second bond-site(block 710), disposing an encapsulant adjacent to the pedestal (block715) and removing at least a portion of the encapsulant to at leastpartially expose the surface of the pedestal (block 720). In certainembodiments, removing at least a portion of the encapsulant includesforming a shallow via through the encapsulant and terminating the via atthe surface of the pedestal. The via can be formed by drilling with alaser or other device, etching through the encapsulant, or anothersuitable method. The process further includes forming a redistributionstructure connected to the surface of the pedestal and the firstbond-site, the redistribution structure having a third bond-site spacedapart from the die between the first and second bond-sites (block 725).In certain embodiments, the process can further include coupling aconductive member to the exposed surface of the pedestal in the via.

FIG. 8A is a cross-sectional view of a semiconductor assembly 800configured in accordance with another embodiment. The assembly 800includes a first package 810 a attached to a second package 810 b, eachof which is individually protected by a corresponding encapsulant 814.The first package 810 a and the second package 810 b each include a die812 that is generally identical in size and configuration. The secondpackage 810 b is generally similar to the first package 810 a, exceptthat the second package 810 b has a footprint that is smaller than afootprint of the first package 810 a. For example, the first package 810a can include first bond-sites 811 at a periphery of the first package810 a, and the second package 810 b can include second bond-sites 813 ata periphery of the second package 810 b. The first bond-sites 811 andthe second bond-sites 813 can have different widths W. For example, thewidth of the first bond-sites 811 can have a first value W₁, and thewidth of the second bond-sites 813 can have a second value W₂ that isless than the first value W₁. Accordingly, the footprint of the secondpackage 810 b can be smaller than the footprint of the first package 810a, and in the stacked configuration, the first bond-sites 811 overlapwith the second bond-sites 813 along an axis transverse (e.g.,perpendicular) to the first bond-sites 811 and the second bond-sites813. In a particular embodiment, an inner edge of the first bond-sites811 can be directly aligned under an inner edge of the second bond-sites813, and an outer edge of the first bond-sites 811 can be laterallyoffset from an outer edge of the second bond-sites 813.

The dies 812 carried by the first package 810 a and the second package810 b can be known good dies or other semiconductor devices that havebeen tested prior to assembly. Each die 812 also includes die bond-sites816 that are coupled to the first bond-sites 811 and the secondbond-sites 813 through corresponding redistribution structures 820. Theindividual redistribution structures 820 have features generally similarto the redistribution structures described above, e.g., including aconductive layer 818, a dielectric layer 819, and third bond-sites 828.Individual third bond-sites 828 of the second package 810 b can becoupled to an external conductive member 862 (e.g., a solder ball) toprovide an external connection to the assembly 800. Individual thirdbond-sites 828 of the first package 810 a can be covered with anadhesive 824 that attaches the first and second packages 810 a, 810 b toeach other.

The assembly 800 also includes interconnect structures 840 thatelectrically connect the first bond-sites 811 with the second bond-sites813. For purposes of illustration and brevity, two different types ofinterconnect structures 840 (a first interconnect structure 840 a and asecond interconnect structure 840 b) are shown in FIG. 8A on the sameassembly 800. In many cases, individual assemblies 800 will includeinterconnect structures of one type or the other. The first interconnectstructure 840 a (shown on the left of FIG. 8A) can include a wire bond842 that is coupled to the corresponding first bond-site 811 and thecorresponding second bond-site 813. The wire bond 842 can be attached tothe bond-sites 811, 813 using the wire bonding techniques describedabove, including for example wire bonding techniques such as stand-offstitch bonding. The order in which the bond-sites 811 and 813 areconnected can differ. For example, the wire bond 842 can be attached tothe first bond-sites 811 first, and then to the second bond-sites 813,or vice versa. The second interconnect structure 840 b (shown on theright of FIG. 8A) can include a conformal conductive link 844 that isdisposed on and between the corresponding first bond-site 811 and thecorresponding second bond-site 813. The link 844 can be formed usingdeposition and etching techniques, or it can be formed by depositing aconformal conductive ink between the corresponding bond-sites.

After the interconnect structures 840 are coupled to the correspondingfirst bond-site 811 and the corresponding second bond-site 813, anencapsulant 846 is disposed around the interconnect structures 840 to atleast partially encase the first bond-site 811 and the second bond-site813 at the periphery of the assembly 800. By forming the interconnectstructures 840 before disposing the encapsulant 846, the foregoingprocess can avoid some of the challenges described above associated withforming and filling interconnect vias in the encapsulant.

FIG. 8B illustrates a stage in which the packages 810 are singulated soas to have the different sized footprints described above with referenceto FIG. 8A. For the purposes of illustration, packages having differentsized footprints are shown as being singulated from the same workpiece802. One skilled in the art will appreciate that different sizedpackages may be singulated from corresponding different workpieces forincreased production efficiency. The packages 810 can be singulated bycutting the workpiece 802 along singulation lines that intersect thefirst bond-sites 811 and the second bond-sites 813. Generally, theassemblies 810 can be singulated to make the second bond-sites 813smaller than the first bond-sites 811, but in some cases the firstbond-sites 811 may not be cut at all. In certain embodiments, thepackages 810 can be singulated by dicing the workpiece 802 through thefirst bond-sites 811 and the second bond-sites 813 with cutting devices(e.g., wafer saws, blades, lasers, water jets, etc.) having differentwidths. For example, a first device 852 a can have a first width thatremoves a first amount of material M₁, and a second device 852 b canhave a second width that removes a second amount of material M₂ that isgreater than the first amount of material M₁. Accordingly, a package 810that has been singulated with the first device 852 a corresponds to thefirst package 810 a shown in FIG. 8A, and a package 810 that has beensingulated with the second device 852 b corresponds to the secondpackage 810 b shown in FIG. 8A.

In other embodiments, a single cutting device 852 can singulate thepackages 810 and remove the corresponding amounts of the firstbond-sites 811 and the second bond-sites 813 by making multiple passesand repositioning the device 852 between passes. In still otherembodiments, the assemblies 810 can be configured to include the firstbond-sites 811 having the first width W₁ illustrated in FIG. 8A and thesecond bond-sites 813 having the second width W₂ illustrated in FIG. 8A,without cutting through the first bond-sites 811 or the secondbond-sites 813 when singulating the assemblies 810.

FIG. 9 is a flow diagram of a process 900 for forming a semiconductorassembly generally similar to that shown in FIG. 8A. In this embodiment,the process 900 includes singulating a first assembly having a first dieand a bond-site at a periphery of the first assembly (block 905). Theprocess further includes singulating a second assembly having a seconddie generally identical to the first die and a second bond-site at aperiphery of the second assembly, along a singulation line thatintersects the second bond-site (block 910). Singulating the first andsecond assemblies includes separating the first and second assembliesfrom a parent structure (e.g., a wafer) at bond-sites such that thefirst assembly has as first footprint and the second assembly has asecond footprint that is smaller than the first footprint. The methodfurther includes attaching the first assembly to the second assembly(block 915) and connecting the bond-site of the first assembly to thebond-site of the second assembly with an interconnect structure (block920). In certain embodiments, connecting corresponding bond-sitesincludes attaching a wire bond to the corresponding bond-sites. In otherembodiments, connecting corresponding bond-sites includes disposing aconformal conductive link (e.g., conductive ink) between correspondingbond-sites. The method further includes encasing at least a portion ofthe interconnect structure and the bond-sites of the first and secondassemblies with an encapsulant (block 925).

Any of the semiconductor assemblies having the interconnect structuresdescribed above with reference to FIGS. 1-9 can be incorporated into anyof a myriad of larger and/or more complex systems, a representativeexample of which is system a 1000 shown schematically in FIG. 10. Thesystem 1000 can include a processor 1002, a memory 1004 (e.g., SRAM,DRAM, flash and/or other memory devices), input/output devices 1006and/or other subsystems or components 1008. Semiconductor assemblieshaving any one or combination of the interconnect structures describedabove with reference to FIGS. 1-9 may be included in any of thecomponents shown in FIG. 10. The resulting system 1000 can perform anyof a wide variety of computing, processing, storage, sensing, imagingand/or other functions. Accordingly, the representative system 1000includes, without limitation, computers and/or other data processors,for example, desktop computers, laptop computers, Internet appliances,hand-held devices (e.g., palm-top computers, wearable computers,cellular or mobile phones, personal digital assistants, music players,etc.), multi-processor systems, processor-based or programmable consumerelectronics, network computers and minicomputers. Other representativesystems 1000 may be housed in a single unit or distributed over multipleinterconnected units (e.g., through a communication network). Thecomponents of the system 1000 can accordingly include local and/orremote memory storage devices, and any of a wide variety of computerreadable media.

From the foregoing, it will be appreciated that specific embodimentshave been described herein for purposes of illustration, but thatvarious modifications may be made without deviating from the invention.For example, one or more additional semiconductor devices may be stackedon the devices in any of the embodiments described above to form stackeddevices including a greater number of stacked units. Furthermore, one ormore additional semiconductor dies may be stacked on the dies in any ofthe semiconductor devices described above to form individualsemiconductor devices having more than one die. For the purposes ofillustration, many of the foregoing processes are shown in the contextof an individual die; however, these processes can also be performed atthe wafer level. The semiconductor devices may also include a number ofother different features and/or arrangements. Aspects described in thecontext of particular embodiments may be combined or eliminated in otherembodiments. Further, although advantages associated with certainembodiments have been described in the context of those embodiments,other embodiments may also exhibit such advantages, and not allembodiments need necessarily exhibit such advantages to fall within thescope of the invention. Accordingly, the invention is not limited exceptas by the appended claims.

We claim:
 1. A method of forming a semiconductor assembly, comprising:attaching a support member having a first bond-site to a die having asecond bond-site; attaching a wire to at least one of the first andsecond bond-sites; encasing at least a portion of the wire and the firstand second bond-sites with an encapsulant; and coupling a thirdbond-site to an exposed segment of the wire extending outside of theencapsulant.
 2. The method of claim 1, further comprising: forming aredistribution structure at a face of the encapsulant spaced apart fromthe die; connecting the redistribution structure to an intermediatesegment of the wire between the first and second bond-sites; and formingthe third bond-site at the redistribution structure.
 3. The method ofclaim 1 wherein encasing at least a portion of the wire includesencasing the wire so that at least a portion of the wire is exposed fromthe encapsulant.
 4. The method of claim 1, further comprising removing aportion of the encapsulant and exposing an intermediate segment of thewire.
 5. The method of claim 1 wherein: attaching the wire includesattaching a continuous wire bond to the first and second bond-sites, thewire bond having an intermediate segment generally parallel to the die,and wherein the method further comprises: removing at least a portion ofthe encapsulant and at least a portion of the intermediate segment andexposing a first portion of the wire and a second portion of the wireseparated from the first portion at a face of the encapsulant; andforming a redistribution structure at the face of the encapsulant andconnected to the first and second portions of the wire, wherein thethird bond-site is connected to the redistribution structure.
 6. Themethod of claim 1 wherein attaching the wire includes attaching acontinuous wire bond to the first and second bond-sites.
 7. The methodof claim 6 wherein coupling a third bond-site to the wire includesattaching the third bond-site directly to the wire bond.
 8. The methodof claim 1 wherein attaching the wire includes attaching a first studbump to the first bond-site, and wherein the method further comprisesattaching a second stud bump to the second bond-site.
 9. The method ofclaim 1, further comprising simultaneously removing encapsulant andmaterial from the wire to form the exposed segment of the wire.
 10. Themethod of claim 1 wherein: attaching the wire comprises attaching thewire to the first and second bond-sites; and the method furthercomprises simultaneously removing encapsulant and material from the wireto remove an intermediate segment of the wire connecting the first andsecond bond-sites.
 11. A method for manufacturing a semiconductordevice, comprising: connecting a first end of a wire to a firstbond-site on a semiconductor assembly; connecting a second end of thewire to a second bond-site on the semiconductor assembly; encasing atleast a portion of the wire and the first and second bond-sites with anencapsulant; and removing the encapsulant to expose a portion of thewire through an outer face of the encapsulant, wherein the exposedportion of the wire projects beyond the outer face.
 12. The method ofclaim 11, further comprising coupling an interconnect to the exposedportion of the wire.
 13. The method of claim 11 wherein removing theencapsulant comprises planarizing the encapsulant to form the outerface.